1. Technical Field
The present disclosure relates to electrosurgical systems and devices for performing medical procedures. The present disclosure also relates to detection devices for use in connection with electrosurgical devices. More particularly, the present disclosure relates to systems, devices and methods for optical detection of surface contact of an electrosurgical device surface to tissue. The present disclosure also relates to electrosurgical devices including a waveguide with dielectric structures. The present disclosure also relates to electrosurgical devices including a waveguide with removable dielectric structures. The present disclosure also relates to methods of directing energy to tissue using the same.
2. Discussion of Related Art
Electrosurgical instruments have become widely used by surgeons. Electrosurgery involves the application of thermal and/or electrical energy to cut, dissect, ablate, coagulate, cauterize, seal or otherwise treat biological tissue during a surgical procedure. Electrosurgery is typically performed using a handpiece including a surgical instrument (e.g., end effector, ablation probe, or electrode) adapted to transmit energy to a tissue site during electrosurgical procedures, an electrosurgical generator operable to output energy, and a cable assembly operatively connecting the surgical instrument to the generator.
Treatment of certain diseases requires the destruction of malignant tissue growths, e.g., tumors. Electromagnetic radiation can be used to heat and destroy tumor cells. Treatment may involve inserting ablation probes into tissues where cancerous tumors have been identified. Once the probes are positioned, electromagnetic energy is passed through the probes into surrounding tissue.
In the treatment of diseases such as cancer, certain types of tumor cells have been found to denature at elevated temperatures that are slightly lower than temperatures normally injurious to healthy cells. Known treatment methods, such as hyperthermia therapy, heat diseased cells to temperatures above 41° C. while maintaining adjacent healthy cells below the temperature at which irreversible cell destruction occurs. These methods involve applying electromagnetic radiation to heat, ablate and/or coagulate tissue. Microwave energy is sometimes utilized to perform these methods. Other procedures utilizing electromagnetic radiation to heat tissue also include coagulation, cutting and/or ablation of tissue.
Electrosurgical devices utilizing electromagnetic radiation have been developed for a variety of uses and applications. A number of devices are available that can be used to provide high bursts of energy for short periods of time to achieve cutting and coagulative effects on various tissues. There are a number of different types of apparatus that can be used to perform ablation procedures. Typically, microwave apparatus for use in ablation procedures include a microwave generator that functions as an energy source, and a microwave surgical instrument (e.g., microwave ablation probe) having an antenna assembly for directing the energy to the target tissue. The microwave generator and surgical instrument are typically operatively coupled by a cable assembly having a plurality of conductors for transmitting microwave energy from the generator to the instrument, and for communicating control, feedback and identification signals between the instrument and the generator.
There are several types of microwave probes in use, e.g., monopole, dipole and helical, which may be used in tissue ablation applications. A microwave transmission line typically includes a thin inner conductor that extends along the longitudinal axis of the transmission line and is surrounded by a dielectric material and is further surrounded by an outer conductor around the dielectric material such that the outer conductor also extends along the transmission line axis.
Dielectric properties of biological tissues are determining factors for the dissipation of electromagnetic energy in the body. Tissue impedance can vary widely among tissue types and can vary according to the quality and quantity of fluids surrounding the tissue. For tissue ablation purposes, there is a need to match the impedance of the microwave transmission line to the impedance of the tissue.